Apparatus for drying gases



Jan. 13, 1953 E. J. GRIBLx-:R ETAL APPARATUS FOR DRYING GASES 4 Sheets-Sheet 1 Filed Jan. 11. 1947 d, m MN @Zr/M OOR a TLG. r M Mm M, D@ mmm/ Jan. 13, 1953 E. J. GRIBLER ETAL APPARATUS Foa DRYING GASES' 4 Sheets-Sheet 2 Filed Jan. 11, 1947 4 Sheets-Sheet 3 Jan. 13, 1953 Filed Jan. 11, 1947 r2-fruvJan. 13, 1953 E. y. GHIBL'ER i-:TAL 2,625,237

APPARATUS FOR DRYING GASES Filed Jan. 11. 1947 4 Sheets-Sheet 4 HT'roRA/EYJ.

DE RIM/N6 REACT/ VAT/0M Patented Jan. 13, 1953 APPARATUS FOR DRYING GASES Elmer J. Gribler, OFa1lon, and Herman A. Lorenz, Belleville, Ill., assignors to Independent Engineering Company, Inc., OFallon, Ill., a corporation of Illinois Application January 11, 1947, Serial No. 721,508

19 Claims.

The present invention relates to an apparatus for drying and heating gases. Particularly, it relates to an apparatus for drying air, and particularly for drying air o r other gas in oxygen generating systems. It likewise incorporates means for reactivating the drying elements and means for heating air for use in derinoing oxygen columns or other appropriate uses.

It is an object of the invention to provide a single apparatus that can supply a continuous flow of dry air despite the fact that the drying elements become saturated. More particularly, it-is an object to provide a plurality of. drying elements with immediately available connections by which certain of the elements may be used for drying while other elements are being used for reactivation of the drying material, which connections may be readily reversed so that while one set of drying elements is supplying dry air the other set may be being reactivated. A particular object is rto provide an apparatus that can produce dried gas for delivery from one element, and selectively divert a part thereof for reactivation of another element.

In this connection, a further object of the invention is to provide an apparatus for drying air or other primary gas, with alternately operable reactivating means incorporating a heater to receiveY a reactivating gas,'=such as nitrogen, or a part of the primary gaa-heating the same, and discharging it into another drying element for reactivation thereof while fthe one is delivering a iiow of dry gas. A further object is to provide an apparatus of this kind wherein automatic time, temperature and pressure control of the gas heating means is provided. y

A further object is to provide in such an apparatus connections by which heated gas Amay be supplied in the air outlet line for use in deriming an oxygen columnor other appropriate use. A further object is to provide a system wherein part of the heated gas may be diverted through another tank to reactivate the same.

Another object is to provide a structure for an apparatus of this kind wherein operating parts are readily replaceable.

Further objects will 'appear from the description to follow. In the drawings:

Fig. 1 is a front perspective 'of the apparatus;

Fig. 2 is a back perspective thereof;

Fig.3isaside view;

Fig. e is a. secti-on on the line 4 4 oiv Fig. l, showing the interfit -of the outer sheeting;

Fig. 5 is a` section 'on the line 5-5 ci Fig. l,

. showing the intert of sheeting;

Fig. 6 isa plan View of-the apparatus with the sheeting removed;

Fig. 7 is a front elevation with the sheeting and insulation removed;

Fig. 8 is a side elevation taken from the right of Figs. 1 and 7;

Fig. 9 is a horizontal section taken on the line 9-9 of Figs. 7 and 8;

Fig. 10 is a horizontal section taken on the line Illl0 of Figs. 'I and 8;

Fig. ll is a vertical section through one of the filter elements;

Fig. 12 is an end View of the lter element taken from the rleft of Fig. 6;

Fig. 13 is a section view of a head for one of the filters;

Fig. 14 is an airflow Idiagram foi` the delivery of dried, heated air or other gas to an o-utlet, such as an air -supply line for an oxygen column;

Fig. 15 is an airflow diagram for the delivery of dried air to an outlet, from one treating tank, and for the simultaneous reactivation of the drying material of the other tank [by the delivery therethrough of heated dry nitrogen; and

Fig. 16 is a wiring diagram of the mechanism.

The principal structural parts of the apparatus are shown in Figs. 6 through 13. In the views, the outside sheeting that forms an enclosure for the entire framework, and the insulation therein, are not shown.

The apparatus is mounted in a frame that includes four vertical corner columns 2B, 2 l, 22 and 23 that are formed of angle irons. These four columns extend to the licor and preferably have feet 24 at their .'bottoms.

Near the bottom, the four columns are joined by angle beams 25, 2E, 21 and 28. These parts are welded together. Mounted below the four angle beams mentioned is a partition plate 30. These various parts, as are the others unless otherwise described, are preferably welded together.

Spaced above the parts thus described are another set of transverse angle beams 32, 33, 34 and 35. Across the Vtop of these angles, there is another partition 36. The rear transverse beams 28 and 35 are connected by vertical beams 39 and il. These vvertical beams are preferably bolted in place so as to be removable to give access to the parts within the frame.

Across the two backv columns 22 and 23 slightly above the partition 36, a channel beam 4i is attached. A channel beam 45 extends across'between the two front columns 20 and 2l above the foregoing. At the side, the columns 2o and 22 are connected by a somewhat wider channel beam 46. A similar wider channel beam 41 joins the columns 2| and 23. At the rear, a wide channel beam 48 extends between the columns 22 and 23.

The front and rear beams 45 and 48 are welded in place in the framework. The two beams 48 and 41 are removably held to the columns 20 and 2| in the following manner: There-is a small outturned channel piece 50- that is welded to each of the columns 20 and 2|. The web sides of the transverse channels 46 and 41 have screws 5| welded thereto and sized to project inwardly through suitable openings in the channels'50 so that they may receive nuts 52 that 'secure `the ends of the beams 45 and `Y41 to the framework. The result is that the forward ends lof thetw'o channel beams 46 and 41 are removably securely held to the columns 20 and'2l.

As shown in the broken-away part of Fig'. I and in Fig. 9, upper and lower attachment plates 55 and 56 are welded to the upper and lower flanges of each of the channel beams 4G and`41. These pairs of attachment plates engage across the upper and lower iianges of the back channel beam 48 at its respective ends, andare bolted thereto by removable bolts 58. By this arrangement, the two side beams 45 ande? may be removed and replaced at will.

The front beam 45 vrests uponthe upperends of the two inner column beams' |58 and 6 These two beams extend down to the front beam 32 and rest upon the top thereof with the partition 35 intervening. These columns may be Vbolted at their respective ends.

At the rear, the beam 48 is supported on two column beams S2 and B3 that extend downwardly to the channel beam 4| extending across the back o the frame. The beams 52 and 65 may be bolted at their upper and lower ends.

At the top of the machine, the front columns 20 and 2| are connected by a channel beam 65. There are side channel beams 8S and 61 likewise at the top between the columns 2G and 22, and the columns 2| and 23, respectively. At the back, there is a channel beam 168 extending inwardly from the 4corner column I22 and joined to a front andvrear channel 68. A similar channel 10 extends in from the corner column 23 and is joined to a front and rear channel 1|.

The intersecting corners of the beam sets just Ydescribed are supported by inner rear columns 12 and 13. These columns extend downwardly, and are bolted to the back channel 48 at-their bottoms, and at their tops are attached as `by welding to the intersecting channel beams v58 and E5, and r1|! and 1|. Additionally there are two inner upper columns 14 and 15 vthat extend from the'beam 45 to the beam 65, at the junctions between that beam 65 and the beams 69 and 1|.

The foregoing forms a frame in which the operating Vparts are supported. Certain elements of the frame are removable. It will be understood'that this frame is covered with removable sheet metal covering which adds to its strength, and, in some cases, aids in the support of operating parts. This sheeting will be described hereafter. Insulation is packed around the operating parts.

There are two tanks 'i8 and 18 supported `in the frame. Each tankhas a converging bottom that partially nts througha properly sized opening in the partition '36, typified by the opening shown approximately'by the reference number 80 in Fig. 1G. These openings thus engage the lower parts of the tanks and give vertical support to them.

'Ashort distance above lthe partition 36,"each and are attached to the back channel section 4|, as shown in Fig. 8. This form of attachment is the same as will be described more fully in connectionwith the-upper straps. y I

Adjacentfthe back channel beam "43,'the tanks are additionally strapped by straps 84 and 85. These straps, like the straps 82 and 83, are in the form of U-bolts having their ends threaded. These'ends pass through openings in the back 'channel 48to`which they are attached by nuts '88.

Spacer blocks"81 are interposed between the backs 'dfi-the' tanks and the back channel beams 4| a'nd'48. -B'ythis arrangement, the straps 82, 83, 84 and Y85 securely but removably attach the tanks into 'the frame.

Between the two tanks 18 and 19, there is an electric heater means 90. It comprises a tank or containerwith heatingcoils in it. This heater is strapped Vremovably to the beams 4| and 4S by straps 9| and 92sthat are similar to the straps for the tanks. `A'spacing block 93 is employed between the tank and each of the two cross beams, sothat the heating chamber may be securely held and clamped to the framework.

A switch box 94 is mounted between the beams 30 and 6| just below the front channel beam-45, and in front of the heater S0. A safety switch is mounted on the beam 15 at the top and back of the frame. I

The piping connections may be best understood by a primary reference to Fig. 15. 'In this Fig. 15, the two driers are indicated at'18 and 19 and the heater at 80.

There is an air or other primary gas inlet leading into the top of the apparatus indicated at |00. It is adapted for connection to an air pump or the like., It leads toy a T |0| from which a left hand branch |02 leads to -a manual valve |03 that isvconnected to a T |35. Apressure gauge line |08 leads from the T |05 to a pressure gauge |01. The T; |05 is likewise connected by a line ||2 into the top ofthe drier tank 18. There is an additional branch from the rstmentioned T |0| comprising a pipe |8 that vleads through a manual valve H9. The other side of this manual valve isrconnected by a pipe |20 to a T |2|. From this Tgapres'suregauge line |22 leads to avpressuregauge |23. The T |2| is likewise connectedV by a pipeA |21 into the top of the other drierftank 19. Y

Also at the top of the tanks, there is a vpipe |32 that,vin the particular use of this apparatus, consists of a secondary or reactivating gasoutlet. This pipe is connected to `a T |33. From this T, a left hand branch |34 leads to ayhand valve |35. This hand valve is connected by a pipe |36 to the line ||2 that extends into the top ofthe drier y15. A right hand branch from the T |33 leads through a pipe |38 toa hand valve |40 that is connected by afpipe |4| to thefpipe |21 leading into the top of the drier 19. Y

The bottom vvconnections from the two drier tanks 18 and 19 are as follows: vFrom Vthe bottom of the drier 18, there leads an outlet |45. This extends into one end lof -a lter |49. n The outlet -of this filter is shown at |50, it leading to a T |5|. From this T, a line |52 leads into ahand valve |55 that, in turn, is connected toa T |51. From the T |51, a pipe |58 leads to another T |59, from which a connection leads to a hand valve |60. The other side 'of the hand valve |60 is connected to a T |6|,'fro'm 'which an air outlet line |62 extends. This line `is 'adaptedto beconnected into a liquid oxygen column'r like `vcnsuming device.

The other drier 19 has an outlet |64 that leads to a lter. |61 like the previously mentioned filter. The outlet of this lter leads at |68 to a T |69l from which a line |10 leads to a hand valve |13. The other side of this hand valve is connected to the T |51, so that the foregoing piping leads to the air outlet.

The T |5| leading from the left hand filter |49 is connected to a hand valve |16. This, in turn, is connected by a pipe |11 to a T |19. This T is connected by a pipe |80 to another T I8 I, from which a line |82 leads into the bottom of the heater 90.

The T |69 below the right hand lter |61 is connected by a line |83 to a hand valve |84, from which a pipe |85 leads to the T |19, so that this drier may alternately be connected into the bottom of the heater.

The T |8| belowthe heater 90 has a pipe |81 leading from it to a hand valve |88. This hand valve is connected by a pipe |89 to the T |6| in the air outlet line.

On the side of the valve |60 opposite the T |6|, there is a pipe |90 leading from the T |59. The pipe |90 is connected to a hand valve |9|, the other side of which is connected by a pipe |92 into a T |94. This T is connected by a pipe |96 into a pipe |99 leading into the topof the heater. The T |94 is likewise connected to a reactivating gas inlet line |95 that is controlled by a hand valve 200. Conventionally, this hand valve 280 will be found at the nitrogen outlet of the column.

The actual structurel disposition of these piping connections is shown in Figs. 1 through 8. The primary gas inlet connection leads from a union that is adapted to be connected to a supply of gas under pressure. In the operation to be described, this supply will consist of an air pump. The line |00 extends to the T |0|. From it, as shown in Fig. '1, the left pipe |02 leads to the hand valve |03. A pipe |04 leads from the valve |03 to the T |05. The pressure gauge line |06 leads from this T to the pressure gauge |01. Upwardly from the T |05, a connection |08 leads to a union |09, thence by a connection I|0 to a T Upwardly from this T, the line ||2 extends through a union ||3 to a T ||4, from which a pipe leads into the top of the tank 18. The T ||4 has a ller plug ||6 removably inserted in its top. The unions |09 and ||3 enable the threaded connections at the other points to be made.

Returning to the inlet line |00, at its T |0|, the right hand line ||8 leads to the hand valve ||9, from whence the pipe connects to the T |2|. From this T, the pressure gauge line |22 leads to the pressure gauge |23. Above the T |2 l, there are connections through a union to a T |26. From this T, the inlet pipe |21 leads upwardly through a union |28 to a T |29 and a connection |30 into the tank 19. A filler plug |6 is located in the top of the T |29.

The nitrogen or secondary gas outlet |32 leads from the T |33. From the T |33, the left hand line |34 leads to the hand valve |35, from which the pipe |36 connects into the T of the line |2 leading into the tank 18. From the right side of the T |33, the pipe |38 leads into a union |39 that is connected to the hand valve |40, the other side of which is connected by the pipe |4| into the T |26 and thence into the inlet line |21 of the tank 19. The union enables the various threaded connections to be made.

While the reference numbers derived from the 6? diagrams of Figs. 14 and l5 are applied on Figs. i' and 8 to the connections below the tank 18, a clearer showing of the structural arrangement is obtained by considering the piping below the tank 19, as these constructions are parallel.

The outlet |64 from the tank 19 leads through a union |65 that is connected into a T |66, having a clean-out plug on its lower side. This T |66 is connected directly into the lter |61. The outlet |68 of this filter leads to a T |69 (Figs. 7, 8, 10). From this T, the line |10 extends downwardly through a union |1| and through a, pipe |12 to the hand valve |13 that is connected by the pipe |14 into the T |51.

The T |69 leading from the outlet side of the lter |61 is connected by the pipe |83 to the hand valve |84. This valve is connected by the pipe through a union |85a to the T |19. This T has the pipe |80 connecting through the T |8|, from which the vertical pipe |82 leads, through a union |83 into the pipe |84 entering the bottom of the heater 90.

The T |8| beneath the heater has an outlet pipe connected through a double elbow arrangement |86 to the pipe |81 leading through a union to the hand valve |88. The outlet of the hand valve |88 is connected by the pipe |89 to the T |6 l.

The T |59 behind the frame is connected by the pipe |90 to the hand valve |9|. The hand valve |9| is connected through a union, by the pipe |92, through a double elbow |93, to the T |94. The secondary gas inlet |95, controlled by the hand valve 290, leads to this `T |94. The pipe |99 rises from this T |94, and is connected to a T |91 that has a relief valve |98 on one side and the pipe |99 leading into the top of the heater at the other side.

In the foregoing, reference has been made to the two lters |49 and |61. These are of identical construction, shownin Figs. 11-13. Each comprises a body 205, preferably of cylindrical seamless metal tubing, into 4which a flange 206 is formed or welded. An end closure 201 may be welded into place. The inner diameter' of the open end is enlarged, and provides a shoulder 208, to which an anchor ring 209 is welded.

A filter element 2 0, preferably of frusto-conical shape, with a flange at the open end thereof, fits into the casing body 205. The element 2|0 ismade of a suitable compressed material forming a rigid permeable lter. It is removably clamped in place by screws 2|| through a clamping retainer ring 2 2, the lter element flange, and the anchor ring. The shape of the element 2 I 0 makes it readily removable and replaceable.

The filter casing 205 is closed by a removable head plate 2 3, adapted to receive screws (Fig. 12) engageable in the ange 206, with a suitable gasket interposed.

The filter casing has an inlet opening 2|4 for connection with either inlet line from the tanks, and anoutlet opening 2|5 for connection with the lines to the hand valves. The designations of inlet and outlet are for convenience, as the filters are subjected to reverse low. It has an end opening 2|6 for receiving vblow-out lines 2|1 or 2|8 that lead to hand valves 2 9 and 220, respectively (Figs. 7, 8). These filters are disposed so that their heads 2 |3 are accessible from the back of the apparatus, and the filters can be serviced at any time.

There is a thermometer 223 connected into the T |19 to indicate temperatures of the gas coming from the heater.

The wiring of the apparatus is indicated in Fig. 16; There are. there shown three-phase power lines 231|; These power lines run through main fuses 23| andthence are connected to two parallel three-phase relay switches 232 and 233. From these switches, the lines run, respectively, through heaters 234 and 235 that are Y-connected. The two heaters 234 and 235 are located within the heater SB, which consists of a hollow container through which gas may flow, over the heater coils. to become heated. It will be seen that the two heaters 234 and 235 are separately connected, each to be operated when its relay switch 232 or 233, as the case may be, is closed.

Across two of the power lines, there is connected the primary of a transformer 231. The secondary of thisl transiorrru-zr has a rst lead 238 extendingto a switch 239; The other side of this switch .is connected to a line 240 that leads through the coil 24| of the relay, which coil actuates the switch 232 in theY high power line. The other side of the relay coil 24| is connected by a line 242 that extends back to the other Vside of the secondary. An indicating lamp 243 is connected across the lines 24i'and 242 so that it is in parallel with the relay coil 24|.

There is another lead 245 extending from the left side of the transformer to a switch 246. The other side of this switch is connected by a line 241 to a timing switch 248. The other side of this switch is connected lby a line 249 to a thermostat 250. This thermostat is located to respond to temperature of thegas coming from the heater. Its connecting .line appears .at 25| (Fig. 8). The otherside of the thermostat is connected by a line 253through a relay'coil 254 that operates the relay switches 233. The other side ofthe relay coil 254 is connected by a line 255 back to the secondary. An indicating lamp 258 is connected across the lines 253 and 255, so as to be in parallel with .the relay .coil ,254.

Thegpreferable form of .paneling for this apparatus is shown .in Figs. 1-5.

There are lower and upperfront panels 25| and 262; These panels are overlapped at their junction, as shown in Fig. 5,` so they can be screwed jointly tothe beam 32, with a smooth surface aiorded by they offset of the edge of the lowerpanel. They are both provided with lateral angesiZEB, appearing in Fig. 4. These flanges 263 overlap oiset edges of two side panels 264 and 265. There are six back panels, 266, 261, 268, 269, 213 and 21|. The panels 266 and 268V enclose the back ofthe lower piping compartment between'the partitions 3B and 36. The back panels 268 and 269 enclose the middle of theback, up to the top of the channel 48. The panels 21o and 21| enclose the backs of the top parts wherein the tanks 18 and 18 extend.

There are inner vertical panels 214 and 215, that have extensions 216 and 211' extending across to interiianges bolted together just below the top' of the heater 90, they being cut away for receivingthe heater top. Top panels 286 and 28| enclose the tops of these parts.

The various panels are cut away to receive the valves, switch box, gauge dials, filter heads, and extended piping. The panels are secured together and to the frame so as to hold the insulation securely, but all are removable.

Assembly The various working parts are assembled into the frame. All of them are removable.

The tanks 18 and 19 are inserted with. the two-crossbeamsd and. removed. They rest upon the partition` 38, and are given full sup` port when the U -bolts Aare fastened. The beams 46 and 41 are then replaced. The height of the tanks relatively to the space between the partition 36 and the top cross beams 66 and 61 permits the foregoing.

The heater may be installed and removed from the top, above the panel extensions 216 and 211, and secured by its U-bolts. Support is aided by the piping connections.

The upper piping is installed in the manner that is apparent. Unions are used to enable connections to be made where alignment of screwed iittings would be diiicult. The valves are :individually removable for servicing.

The lower piping is largely welded or otherwise permanent, except for the unions. Each filter assembly is removable with its connections as a unit. Thus the union |65 below the tank 19, the union 11|, and the union |85a may be released, and the filter |61, together with the indicated pipes, Ts and the valve |84, removed, for necessary servicing. In similar fashion, the central pipe network below the heater may be removed as a unit by releasing the unions |83, |18, |8511l and the union in the pipe |81. The two lower valves |55 and |15 may be removed by release of the union |1| and its counterpart, and -of the pipes |56 and |14.

The foregoing not only facilitates servicing, buta-ifords less possibility of leakage. The outer panels are divided to enable the particular parts requiring service to be removed without disasassembling the entire structure. Itis particularly to be noted that the lower piping compartment is partitioned oi, so that it may be completely serviced without disturbing the upper assembly. The entire casing is packed with insulation.

Operation While this apparatus is capable of a number of uses, it is designed for the particular use in connection with the supplying of dried air or dried heated air to an oxygen producing column, or with the drying of gas in oxygen systems. Consequently, it may be interposed into a line between the supply pump of air and the oxygen column. The drier tanks 18 and 19 are iilled with some drying agent, such as activated alumina, which is subject to deactivation after a period of use. This alumina may be reactivated by being subjected to a stream of gas, such as the nitrogen take-off from the liquid oxygen column that is heated, or a bleed-off of air dried in the tank supplying the same. As is evident already, the reactivating gas iiow is preferably counter to the' iiow of the air through the drying tanks.

Afurther use of this device is in connection with the deriming of the oxygen column or production of heated, dry gas for other uses. Deriming is accomplished by directing dried heated air through the column. Its use will be iirst described as applied to the delivery of dried air to a liquid oxygen column'.

For the primary operation of supplying -dried air for the production of liquid oxygen in the column, the apparatus is designed so that one of the two drying tanks is always available for the supplying of the'dried air. This is accomplished by the piping hook-up or network, by the connections of which the tankV not in use to vsupply the dried air is connectedffor reactivation vby nitrogen from the column...

VSuch operation is diagrammatically shown in Fig. 15.

When the apparatus is started with no pressure in the main air line |00, the air valves |03, |55 and |69, and the nitrogen valves 200, |84 and |40 are all open. The air valves ||9, |13, ISI and |88, and the nitrogen valves |16 and |35 are closed. When the air compressor is started, the air will then flow from the compressor through the supply line |00, to the T thence through the valve |03 and by way of the inlet ||2 to the top of the drier 18.` This ow of air is obstructed from the other drier by the closed valve ||9. It is also prevented from running into the nitrogen outlet line by the closed valve |35. From the bottom of the drier, the air passes out the outlet |45 and into the filter |49. From this lter, it ows out the line |50 and down through the open valve |55, thence to the T |51, and, by the line |58, through the valve |60 to the air outlet |62.

This discharge from the drier A, consisting of dried air, is prevented from leaving the foregoing discharge course by the closed valves |16, |13, |88 and |9I.

Assuming at this time that the drier tank 19 has been deactivated, a supply of dry nitrogen is passed backward through it. This nitrogen enters past the valve 200 in the nitrogen inlet line |95. t passes thence through the line |96, being cut ofi' from the outlet by the closed valve |9I. It then flows into the top of the heater 99 by way of the inlet |99 ther-cinto. In this heater, it ows across the heating elements, as will be described, becoming heated, and thence out through the outletl pipe |82 to the T |19. It is prevented from bypassing through the line |81 connected into the outlet |82 by the closed valve |98. From the T |19, it is also prevented from passing to the other drier tank 18 because of the closed valve |16. It does flow through the open valve |84 and thence to the T |69. It cannot flow to the outlet line from the T |69 because of the closed valve |13. It, therefore, flows through the lter |61 backward, and thence into the discharge outlet |64 of the drier 19. It passes through this drier in the form of heated, very dry gas, so that it may take up the moisture from the alumina therein. It flows out the top inlet |21 of the tank 19. It is prevented by the closed valve ||9 from running into the air inlet,so that it must flow through the open valve |40 to the nitrogen outlet |32.

The foregoing air and nitrogen flow is continued until the alumina in the tank 18 becomes loaded with moisture drawn from the air. Then 'the valving is reversed, so that the air iiows from the air inlet |90 to the drier 19, the lter |61 and to the outlet |62; and s'o that the nitrogen flows through the heater and therefrom backward through the drier 19 and ultimately out the nitrogen outlet |32.

If there is pressure in the air supply line |00 at the time the driers are placed in service, it is lnecessary to start out with the airA line valvesv all closed. In particular, this will mean that .and |60 are closed. The rst operation is to vcrack the Valve |03 and allow the air to nowv slowly past this valve into the drier 18. `When the drier has built up the main line pressure, as

indicated on the pressure gauge |01, the valve |93 is opened wide. Then the valves |55 and |60 are opened slowly to put this drier 18 into service. The nitrogen supply valve 200 is open, the valves |84 Aand .49 .are open, and the nitrogen supply will 10 then flow through the heater and backwardly through the drier 19 to reactivate the alumina therein.

In reversing the operation to shift from drying air in the drier 18 to drying it in the drier 19, which may take place after approximately eight hours of drying service from the drier 18, the valves |84 and |49 are closed tight. The valve |13 is cracked, so that high pressure air slowly flows backward through the filter |61 and into the tank 19, building the pressure therein slowly until it attains line pressure, as shown by the pressure gauge |23. Then the valve I9 is opened, so that air passes through both driers. Thereafter, the valves |63 and |55 are closed. This leaves the drier 19 in service, supplying dried air to the air outlet |62 and the column.

Thereafter the valve 2| 9, which is the blow-01T Valve for the filter |49, is open momentarily, so that the air under pressure-in the tank 18 blows out any dust entrapped in the lter. The valve 2| 9 is then closed. The valve |35 is then cracked, allowing the remainder of the air under pressure in the tank 18 to blow out through the outlet line |32 and slowly relieve the pressure in the tank 18. When all of the pressure is out of the tank 18, the valves |35 and` |16 are open wide, so that nitrogen flows from the heater through the drier 18 and out the outlet |32. Thereafter, the drier 18 Awill be reactiva-ted, while the drier 19 supplies dry air to the air outlet.` It will be noted that all of the great pressure changes in the filter tanks are made slowly so that the alumina will not become powdered. v

The foregoing air and nitrogen flow is under the further control of the electrical system shown in Fig. 11. The heating elements of the heater are put in circuit by operation of their switches. At the start of any reactivation of either drier, the timing switch 248 is turned to a chosen point, such as a point that indicates a four-hour operation. Such timing switches are conventional in the art and usually involve the turning of a handle over a dial to the indication desired. Then the toggle switch 24S-is closed. When this is done, the heater 235 will be put in circuit as the closure of the two switches 243 and 246 `closes the secondary circuit through the relay coil 254, and this coil closes its switches 233 to put the heater 235 in the primary high-powered lines. It will also be observed that the lamp 256 will be energized to indicate the operation of this circuit. It will also be observed'that this circuit passes through the thermostatZEll,l which is an indicator of the temperature of the nitrogen being heated. Prcf' The temperature of the nitrogen will be a funcl tion of the amount of ilow. The valve 290 should be adjusted -to maintain a temperature in the' nitrogen of between 425 and 450 F. If the now is too small,- the temperature will rise, and', `when it reaches 475, will cause the thermostat 250 to open and shut oi'thecircuit to the heater235.y

When the temperature thendrops to 450the circuit will reclose and start the Vheater again. If too much nitrogen is passed through the heater, it will not be sufficiently warm to reactivate the bed of alumina. Hence, thel valve 200 should be properly regulated `to maintain thev temperature within the range noted, Aas indicated by the thermometer.

After the preset four hours of heating, the timer switch 248 automatically opens and cuts oi the heater 235. VThe nitrogen, however, is allowed to continue flowing in order to cool the alumina to atmospheric temperature. This cooling time may be another four hours, so that the total cycle is eight hours in a typical case. At the end of the eight hours, the ilow circuits are reversed in the manner already described.

Another operation that is possible-as a result of the piping network is to bleed off a part of the gas dried from one column, to reactivate the other. A particular value of this is tha-t it may be used where the drier is in a pure gas line, such as an oxygen gas line, because, when a tank is reactivated by the conditioned gas, rather than by a diierent gas, it does not require purging after reactivation of the reactivating gas before the conditioned gas may be passed through it.

If air is being dried through the tank 18. andv the flow path of this air is as indicated in Fig. 15, the valve 200 may be closed. The valve 19| may be opened to admit a small .part (such as in certain installations) of the dried air to iiow from the discharge pipe |53 to the `pipe |36 leading into the heater. This dried air is heated, and flows thence backward through the lter |61 and the tank 13 to reactivate the medium therein. Thence it iows through the outlet |32. If the drier is in an oxygen-gas line `from the column, the moistened oxygen from the line |32 may be forced into suitable tanks for storage, or otherwise used.

The deriming operation is one that illustrates the connection of the heater 90 in series with one of the driers, so that the dried air supplied is also heated. The use of deriming is one that this apparatus is particularly adapted to because it is an operation in the column that normally is supplied with dried cool air.

Assuming the oxygen column to be in proper condition to be derimed, the nitrogen valve 200 is closed, the valves |35, and H9 are closed at the top of the apparatus. and the lower valves |16, |84, |13 and |60 are closed. The remaining valves are open so that the system appears as in Fig. 14. This produces an air now that enters the air inlet |30, passes thence through the valve |03 into the top of the drier 18 (assuming that it is this drier that is to be used in this operation. Of course, the other drier could be used, as is evident). The air iiow from the drier 'i8 passes through the lter |49 and thence past the Valve and the line |58 to the T |59. It is obstructed from the outlet by the closed valve |60, but is permitted to flow upwardly through the line |90 past the now vopen valve |9|. It iiows thence into the heater 90. From the heater 90, it flows through the line |82 to the T |8|. As both of the valves |16 and |84 are closed, it must dow out the line I 31 and past the -now open valve |88 to discharge into the air outlet |62.

In this operation, the electrical parts are operated as follows:

Both of the two toggle switches 239 and 246 are closed. The closure of the toggle Aswitch 23e closes the secondary circuit to the relay coil 24|, which thereupon closes the switches 232 and puts the deriming heater 234 in circuit to be energized. After the column has been partially warmed up by air heated ,from this somewhat smaller deriming heater 234, the timer Switch 2431s turned-clockwise all the way. This will close the secondary circuit of the relay coil 254, which will operate its switches 233 to put the reactivation heater 235 in circuit. Thereafter, the air from .the compressor will be given the total output of both heaters and deriming will be greatly speeded up. When it is complete, the toggle switches 239 and 246 can be opened.

In this operation, the pressure must be maintained at not over 250 p. s. i. The safety valve on the heater 90 isset for 300 p. s. i. and protects the heater.

During this derimingoperation, the other tank 19 may be reactivated. To do this, the valve |84 is cracked to pass a small part of the dry, hot air flowing from theheater. The valve |40 is also cracked, or opened. This small quantity flows upward through the lter |51 and the tank 19, reactivating the dying medium. Thence it flows pass the valve |40 and into the discharge line |32.

After some period of use, such as about a year, the pores of the activated alumina may become plugged with oil and other impurities, and the drying qualities impaired to such an extent that replacement is required. To do this, the panels are removed from the lower part of the frame and the insulation is withdrawn. The two drain plugs 48 at the bottom of the two Ts |41 and |66, with their lter screens (not shown), are removed, and the alumina in the two tanks is permitted to run out. Thereafter the filter screens and plugs are replaced, sealed into place, the insulationand panels are replaced. Then the iilter screens and filling plugs I It at the top of the two tanks are removed, and new alumina is placed in the cylinders to fill them. It will be, observed that the lateral connections of the inlet and outlet lines into the unions leading to the tanks, and the axial disposition of the plugs enable the foregoing operations to be made without the flow of the drying medium into these lines during charging and draining.

At regular intervals, such as once a month, the main lters vshould be checked. The heads 213 of these lters are removed, the screws 2 that hold the lter cones in place are removed, the cone is withdrawn, scraped carefully and washed, such as with carbon tetrachloride. Thereafter, the cones are dried with air and replaced.

It will be seen that an apparatus has been provided which can supply a continuous flow of dried air. It does this by supplying the air selectively through onevdrier, while reactivating the other drier` It also may be used to supply heated air where such is desired. It provides a high degree of automatic control of its operations. It is relatively compact, so that all of the foregoing' functions may be obtained from a single apparatus with a minimum of bulk and complication.

What is claimed is:

l. In an apparatus for drying and heating gas, a pair of'tanks for containing an adsorbent treating medium subject to deactivation, a main ges inlet for delivering an untreated gas to the apparatus, a valved connection from the inlet to the rst end of each tank for selectively directing the untreated gas to either of said tanks, a secondary outlet for discharging a spent reactivating gas from the apparatus, a valved connection from the secondary outlet to the iii-st end of each tank for selectively discharging a spent reactivating gas from either of said tanks into said secondary outlet, a main gas discharge line for delivering a treated gas from the apparatus, a valved connection from the second end of each tank to the discharge line for selectively delivering a treated gas from either of said tanks to said discharge line, a heater for conditioning a treated gas to reactivating condition, an inlet to the rst end of the heater for delivering an unconditioned treated gas thereto, a valved connection between the second end of the heater and the second end of each tank for selectively delivering a reactivating gas to either of said tanks, and a valved connection between the main gas discharge line and the heater inlet for selectively delivering a treated gas to the heater, whereby a portion of the treated gas from said discharge line may be bypassed through the heater.

2. In an apparatus for drying gases,` a rst tank, a second tank, an inlet and an outlet to each, each tank being adapted to contain an adsorbent material subject to deactivation, a primary gas supply connection, a primary gas discharge connection, a rst set of valved conduits between the primary supply connection and the inlet to each tank and a second set of valved conduits between the primary gas discharge connection and the outlet of each tank whereby the primary gas may be selectively directed through one tank and cut oif from the other, a reactivating gas supply connection, a reactivating gas discharge connection, a third set of valved conduits between the reactivating gas supply connection and one of the aforementioned sets of valved conduits and interposed into the latter between the respective valves thereof and the tanks and a fourth set of valved conduits between the reactivating gas discharge connection and the other of the two rst mentioned sets of valved conduits and interposed into said other of the two iirst mentioned sets of valved conduits between the respective valves thereof and the tanks whereby reactivating gas may be directed through the other tank while the one is receiving primary gas, heating means for the reactivating gas interposed into the reactivating gas supply connection ahead of said third set of valved conduits, and selectively operable means, including a valve in the primary gas discharge connection, a valved conduit from said latter connection ahead of said valve therein and leading into the heater, and a valved conduit leading from the heater and connected into the primary gas discharge connection behind said valve therein, for directing some of the primary gas through said heating means in the absence of reactivating gas flow therethrough.

3. In an apparatus for drying and heating gases, a tank, a first conduit for introduction of primary gas into the tank, a rst valve in said rst conduit for selective employment thereof, a second conduit for discharge of primary gas from the tank, a second valve in said second conduit for selective employment thereof for discharge of primary gas, a third conduit for introduction of a second gas into the tank, said third conduit being connected into the tank in parallel with said second conduit, a third valve in said third conduit for selective employment thereof for introduction of a second gas, a fourth conduit for discharge of the second gas from the tank, said fourth conduit being connected into the tank in parallel with said first conduit, a fourth valve in said fourth conduit for selective employment thereof, and a now-through heater, one side of the heater having a valved connection with said second conduit ahead of said second valve, the otherside of the heater having a valved connection with said second conduit behind said second valve, the heater being also interposed into said third conduit ahead of said third valve for selectively heating said second gas prior to its introduction into the tank.

4. In an apparatus for drying and heating gases, a tank for containing an adsorbent, conduit means having selectively operable valves for selectively passing a rst gas through the tank, other conduit means having selectively operable valves for selectively passing a second gas through the tank, and a heater disposed in said other conduit means, said conduit means aforementioned including selectively operable connections for selectively passing a rst gas through the heater afterpassage through the tank and including also connections for selectively passing a second gas through the heater prior to passage through the tank.

5. In an apparatus for drying and heating gases, a tank having two `ropenings thereinto, means for connecting the tank into a first gas flow line, valves in the inlet and outlet sides of the connecting means, second means for connecting the tank into a second gas flow line, valves in the inlet and outlet sides of the second connecting means, a flow-through heater, and selectively operable means for selectively introducing the heater either into the outlet side of the first gas ow line or the inlet side of the second gas flow line.

6. In an apparatus for drying and heating gases, a tank for containing an adsorbent, conduit means having selectively operable valves for selectively passing a iirst gas through the tank, other conduit means having selectively operable valves for selectively passing a second gas through the tank in a direction counter to said passage of the first gas through the tank, and a heater disposed in said other conduit means, said conduit means aforementioned including selectively operable connections for selectively passing a first gas through the heater after passage through the tank and including also connections for selectively passing a second gas through the heater prior to passage through the tank.

'7. In an apparatus for drying and heating gases, a iirst and a second gas drying tank, each having an inlet and an outlet, a rst gas inlet branching to both tank inlets and having a valve for each branch, a second gas outlet branching from both tank inlets and having a valve for each branch, a first gas outlet branching from both tank outlets and having a valve in each branch, a second gas inlet branching to both tank outlets and having a valve in each branch, a heater in the second gas inlet disposed ahead of the branches thereof, a supplemental valve in the rst gas outlet, a valved connection between the rst gas outlet ahead of the supplemental valve and the second gas inlet ahead of the heater, and an additional valved connection between the second gas inlet behind the heater and the rst gas outlet behind the supplemental valve.

8. A. gas drying and heating apparatus including two gas drying tanks and a heater, conduit means for passing a rst gas through either tank, said conduit means having valve means whereby said first gas may be passed through one of said tanks and cut -oif from the other, said valve means being reversible whereby said first gas may be passed through the other of said tanks and cut olf from the one, other conduit means for passtank, said otherl conduit means having valve means similarto vthe previously mentioned lvalve 'means whereby said "second ggas may be passed fromv the heaterthrough either one of said tanks `and cut'oi'from theother, selectively operable means whereby said first gas may be passed through either tank and the heater, said heater having electric heating coils therein, means for vselectively operating said coils to produce Vone heating capacity for the nrst gas, and means for operating the .coils to produce a different, heating capacity for the second gas.

9. In an apparatus for drying,r and heating gases, a frame, apair of gas drying tanks on the 'framea heater on the frame'a'rst gas inlet pipe having a'rst gas .inlet branch into each tank,'a:rst `gasinlet valve in Veach branch, said valvesbeing supported'on theirs-me, a second gas outlet pipe having' a Vsecond gas outlet branch into each of said rst gas inlet branches between the valves therein and thetanks, a valve in each of .said .second gasoutlet branches, said rst gas inlet 'branches being removably connected into the tops ofthe rrespective tanks, a iirst `gas outlet branch from each tankremovably connected therewith, -al'filterin each of said first gas outlet branches, 'said lters `being separately mounted on'the framea'second gas inlet pipe into the heateiga second gas outlet pipe from the heater having a second gas inlet branchinto each filter, a second gas inlet valve in each of'said latter branches, a rst gas outlet valvein each of said rst gas outlet .branches behind the respective filters therein, :and .anrst gas .outlet pipe c-onnected to both .of said rst gas outlet branches behind .said-'nist gas outlet valves therein.

10. In van apparatus for drying and 'heating gasesia frame, ap'airof gas drying'tanks on the frame, a heater on the frame, a first gas inlet. pipe having a'rst'gas inlet branch into each tank, a rst gas vinlet valve in each branch, said valves being supported on the frame, a second gas outletpipe having a second sas outlet branch into `each of said rst gas inlet branches between the tvalves therein'and the tanks, a Valve in each of said second gas outlet branches, said rst gas :inlet branches being removably connected into 'the'tops ofthe respective tanks, a first gas outlet branch from each tank removably connected therewith, a iilter in each of said rst gas outlet branches, said lters being separately mounted o'n the frame and having removable covers and removable `fdlter elements, said covers and elements being removable from outside the frame, a second gas inlet pipe into `the heater, a second gas `outletpipe from' V.the heater having a secondrgas inlet branch into each lter, a second gas inlet valve in each of said latter branches, a iii-st gas outlet valve in each of said first gas outlet branches behind the respective lters thereimand a rst gas outlet pipe connected to both 'of said first-gas outlet branches behind said first gas outlet valves therein.

1l. In an apparatus for drying and heating gases, a frame, a pair of gas drying tanks on the framasaid framehaving an opening in one side Yfor removal ofthe tanks, a beam across said opening, means removably securing the beam to the frame. means removably securing the tanks to the beam, a heater on the frame, a first gas inlet pipe having a first gas inlet branch into each tank, a nrst gas inlet valve in each branch, said valves being supported on the frame, a secondgas outlet .pipe having a `second gas outlet branch into'ealch of said first gas inlet branches between the valves therein'and the tanks, a valve ineach ofsad secondigas outletlbranches, said iirst gas inlet branches being removably connected into the tops'of the respective tanks, a iirst gas outlet branch 'from each tank removably'connected therewith, a lter in each of said first gas outlet branches, said-filters being sepa rately mounted -ontheii-ame, a second gas inlet pipe into the heater, a second gas outlet pipe from the heater having a second gas inlet branch into each lter, a second gas inlet valve in each of said latter branches, a rst gas outlet valve in each of said first gas outlet branches behind the respective nlters therein, and a rst gas outlet pipe connected to both of said rst gas outlet branches behind said first gas outlet valves therein- 12. A gas drying Vapparatus including a frame comprising two columns up one side, spaced supports, means attaching the columns andsupports including cross beams across said one side, tanks in the frame, said tanks being insertable between the columns andcross beams, 'a removable beam between the columnsacross said one side between the ends oftanks to facilitate by removal thereof the insertion of said tanks in the frame, and means-removably attaching the tanks to the beam iorsecurement oi said tanks in the frame.

13. Inan apparatus for drying gases, a frame. a pair of tanks mounted on the frame with their bottom parts above the bottom of the frame, means on the ram'edividing it into vertical sections, said means being adjacent the bottoms of the tanks, an upper'section pipirrT system leading into the 'tops of both tanks, comprising first gas piping connections including a common pipe, branches leading to the two tanks, and valve means 'to vconnect. the common pipe with either tank and to out it o'i from the other, said upper section piping system comprising also second gas piping connections including a common pipe, branches leading to the two tanks, and valve means to connect the common pipe with either tank andto out it off from the other, a lower section piping system leading into the bottoms of both tanks, comprising third gas piping connections including a common pipe, branches leading to the two tanks, and valve means to connect tl e common pipe with either` tank and to out it oii from the other, said lower section piping system comprising also fourth gas piping connections including a common pipe, branches leading to the two tanks, and valve means to connect the common pipe with either tank and to cut it ci?v from the other, said upper section piping system being disposed in an upper of said vertical sections, said lower piping system being disposed in a lower of said vertical sections, and means enclosing lsaid upper vertical section separately from said lower vertical section, whereby said lower section piping system may be serviced without disturbing said upper vertical section.

14. In an apparatus for drying gases, a frame, a pair of tanks mounted on the frame with their bottom parts above the bottom of the frame, means on the frame dividing it into vertical sections, said means being adjacent the bottoms of the tanks, an upper section piping system leading into the tops of both tanks, comprising iirst gas piping connections including a common pipe, branches leading to the two tanks, and valve means to 'connect the common pipe with either tank and to cut it oifrom the other, said upper section piping system comprising also second gas piping connections including a common pipe, branches .leading 'to the 4two tanks, and valve means to connect the common pipe with either tank and to cut it off from the other, a lower section piping system leading into the bottoms of both tanks, comprising third gas piping connections, including a common pipe, branches leading to the two tanks, and valve means to connect the common pipe with either tank and to cut it 01T from the other, said lower section piping system comprising also fourth gas piping connections including a common pipe, branches leading to the two tanks, and valve means to connect the common pipe with either tank and to cut it off from the other, said upper section piping system being disposed in an upper of said vertical sections, said lower piping system being disposed in a lower of said vertical sections, means enclosing said upper vertical section separately from said lower vertical section, whereby said lower section piping system may be serviced without disturbing said upper vertical section, and separately removable means for enclosing said lower vertical section.

15. In an apparatus for drying gases, a frame, a pair of tanks mounted on the frame with their bottom parts above the bottom of the frame, means on the frame dividing it into vertical sections, said means being adjacent the bottoms of the tanks, an upper section piping system leading into the tops of both tanks, comprising first gas piping connections including a common pipe, branches leading to the two tanks, and valve means to connect the common pipe with either tank and to cut it off from the other, said upper section piping system comprising also second gas piping connections including a common pipe, branches leading to the two tanks, and valve means to connect the common pipe with either tank and to cut it off from the other, a lower section piping system leading into the bottoms of both tanks, comprising third gas piping connections, including a common pipe, branches leading to the two tanks, and valve means to connect the common pipe with either tank and to cut it oi from the other, said lower section piping system comprising also fourth gas piping connections including a common pipe, branches leading to the two tanks, and valve means to connect the common pipe with either tank and to cut it oi from the other, said upper section piping system being disposed in an upper of said vertical sections, said lower piping system being disposed in a lower of said vertical sections, means enclosing said upper vertical section separately from said lower vertica1 section, whereby said lower section piping system may be serviced without disturbing said upper vertical section, and insulation within the upper section about the tanks.

16. In an apparatus for drying gases, a frame, a pair of tanks mounted on the frame with their bottom parts above the 'bottom of the frame, means on the frame dividing it into vertical sections, said means being adjacent the bottoms of the tanks, an upper section piping system leading into the tops of both tanks, comprising first gas piping connections including a common pipe, branches leading to the two tanks, and valve means to connect the common pipe with either tank and to cut it off from the other, said upper section piping system comprising also second gas piping connections including a common pipe, branches leading to the two tanks, and valve means to connect the common pipe with either tank and to cut it off from the other, a lower section piping system leading into the bottoms of both tanks, comprising third gas piping connections, including a common pipe, branches leading to the two tanks, and valve means to connect the common pipe with either tank and to cut it off from the other, said lower section piping system comprising also fourth gas piping connections including a common pipe, branches leading to the two tanks, and valve means to connect the common pipe with either tank and to cut it oi from the other, said upper section piping system being disposed in an upper of said vertical sections, said lower piping system being disposed in a lower of said vertical sections, means enclosing said upper vertical section separately from said lower vertical section, whereby said lower section piping system may be serviced without disturbing said upper vertical section, and a heater mounted in said upper vertical section, said heater having connections to said lower section piping system.

17. In an apparatus for drying gases, aframe, a pair of tanks mounted on the frame with their bottom parts above the bottom of the frame, releasable holding means for securing the tanks to the frame, means on the frame dividing it into Vertical sections, said means being adjacent the bottoms of the tanks, an upper section piping system leading into the tops of both tanks, comprising first gas piping connections including a common pipe, branches leading to the two tanks, and valve means to connect the common pipe with either tank and to cut it off from the other, said upper section piping system comprising also second gas piping connections including a conimon pipe, branches leading to the two tanks, and valve means to connect the common pipe with either tank andto cut it 01T from the other, a lower section piping system leading into the bottoms ofjboth tanks, comprising thirdv gas piping connections, including a common pipe, branches leading to the two tanks, and valve means to connect the common pipe with either tank and to cut it oi from the other, said lower section piping system comprising also fourth gas piping connections including a common pipe, branches leading to the two tanks, and valve means to connect the common pipe with either tank and to cut it oi from the other, said upper section piping system being disposed in an upper of said vertical sections, said lower piping system being disposed in a lower of said vertical sections, means for disconnecting said lower section piping system from the tanks, and removable means enclosing said upper vertical section separately from said lower vertical section, whereby said lower section piping system may be serviced Without disturbing said upper vertical section.

18. In an apparatus for drying gases, a frame, a pair of tanks mounted on the framev with their bottom parts above the bottom of the frame, releasable holding means for securing the tanks to the frame, said holding means including releasable attaching devices between the frame and the respective tanks, said frame including xed members and cross members releasably attached to said xed members at points between the ends of the tanks, means on the frame dividing it into vertical sections, said means being adjacent the bottoms of the tanks, an upper section piping system leading into the tops of both tanks, comprising rst gas piping connections including a common pipe, branches leading to the two tanks, and valve means to connect the common pipe with either tank and to cut it off from the other, said upper section piping system comprising also second gas piping connections including a common pipe, branches leading to the two tanks, and valve means to connect the common pipe with either tank and to cut it off from the other, a lower section piping system leading into the bottoms of both tanks, comprising third gas piping connections, including a common pipe, branches leading to the two tanks, and valve means to connect the common pipe with either tank and to cut it oi from the other, said lower section piping system comprising also fourth gas piping connections including a common pipe, branches leading to the two tanks, and valve means to connect the common pipe with either tank and to cut it off from the other, said upper section piping system being disposed in an upper of said vertical sections, said lower piping system being disposed in a lower of said vertical sections, means for disconnecting said lower section piping system from the tanks, and removable means enclosing said upper vertical section separately from said lower vertical section, whereby said lower section piping system may be serviced without disturbing said upper vertical section.

19. In an apparatus for drying and heating gas, a pair of tanks adapted to contain a gas treating material subject tc deactivation, a valved secondary discharge from the first end of each tank for selectively discharging a spent reactivatlng gas from either of said tanks, a main gas inlet having valved connections to the rst end of each tank for selectively delivering van untreated gas to either of said tanks, a main gas outlet having valved connections with the second end of each tank for selectively delivering a treated gas from either of said tanks, a heater having an inlet connected with the main gas outlet for conditioning at least a portion of said treated gas to re- 3a activating condition, and having an outlet line for delivery of a reactivating gas from the heater, a valved connection between the heater outlet and the second end of each tank whereby the reactivating gas from the heater may be selectively directed through one of the tanks.

ELMER J. GRIBLER. HERMAN A. LORENZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,014,371 Burhorn Jan. 9, 1912 1,541,147 Ikeda et al June 9, 1925 1,581,050 Frick Apr. 13, 1926 1,650,151 Patterson Nov. 22, 1927 1,753,067 Ray etal Apr. 1, 1930 1,863,656 Hartman June 21, 1932 1,934,075 Lewis Nov. 7, 1933 1,948,779 Abbott et al Feb. 27, 1934 1,986,814 Hartman Jan. 8, 1935 1,998,774 Bulkeley Apr. 23, 1935 2,143,949 Keith Jan. 17, 1939 2,222,882 Shames Nov. 26, 1940 2,257,478 Newton Sept. 30, 1941 2,323,524 Downs July 6, 1943 2,354,383 Kiesskalt July 25, 1944 2,370,276 Warren Feb. 27, 1945 2,430,861 Carpenter et al. Nov. 18, 1947 2,535,902 Dailey Dec. 26, 1950 OTHER REFERENCES Ser. No. 33,698, Jaubert (A. P. CJ, published May 18, 1943. 

